Oral medicinal or oral hygiene products exist in a wide variety of forms, such as tablets, capsules, liquids or sprays. When applying the oral medicinal or oral hygiene products in the form of a liquid, typically a measured quantity of the product is applied to the oral cavity by means of a spoon. Unfortunately, such liquids are frequently spilled, especially when they are applied to children or elderly people. Spilling can lead to inaccuracies of the applied dosage. Therefore, much research has been spent on developing new ways of applying liquid oral medicinal or oral hygiene products.
European Patent Application 1,210,935 A1 discloses an oral medicinal composition which comprises an active ingredient and at least one foaming agent, which is ejected from a foam-developing device. The medicinal composition is said to be useful for aged persons, children or patients with swallowing difficulties. A variety of monomeric and polymeric low molecular weight compounds are listed as foaming agents, preferably a mixture of polyethylene glycol and polysorbate or a mixture of polyethylene glycol and sodium lauryl sulfate. When polyethylene glycol is used as a foaming agent, for example polyethylene glycol of a molecular weight of 6000, the duration of the resulting self-sustainable foam is short. When sodium lauryl sulfate or a polysorbate, such as polysorbate 80 with a molecular weight of about 1300, is used as a foaming agent, the duration of the resulting self-sustainable foam is long. EP 1,210,935 A1 teaches that the resulting self-sustainable foam is influenced by the mean molecular weight of the foaming agent. It suggests to prepare a combination of plural foaming agents by utilizing such properties and further modifying the blend ratios or blend quantities to adjust the duration of the resulting self-sustainable foam depending on the applicable drug or the subject patient. It also teaches that the medicinal composition with a longer duration of self-sustainable foam can be achieved by adding an appropriate viscous agent other than a foaming agent. Various polymeric compounds are listed as viscous agents, such as propylene glycol alginate, various cellulose ethers, starches, polyvinylpyrrolidone, or yellow beeswax. However, variation of the duration of the resulting self-sustainable foam by blending a plurality of foaming agents and in some cases a viscous agent in addition to the plurality of foaming agents is inconvenient. Also, the more different types of foaming agents and thickeners are incorporated into an oral medicinal composition, the higher is the risk of incompatibilities.
U.S. Pat. No. 6,086,856 discloses oral hygiene formulations which comprise foaming surfactants. They are dispensed in the form of foams by means of an air-driven propellant-less dispenser. The formulation comprises an oral surfactant, a compound effective for oral hygiene and water containing up to 25 weight percent of ethanol. An anionic surfactant is used, such as sodium lauryl sulfate, alone or in combination with nonionic surfactants, such as poly(oxyethylene)—poly(oxypropylene) block copolymers.
Unfortunately, sodium lauryl sulfate that is recommended in both above-mentioned patent publications as a preferred foaming agent is a moderately toxic material (Handbook of Pharmaceutical Excipients, Fourth Edition, page 569).
U.S. Pat. No. 5,369,131 discloses oral, cutaneous and intravaginal pharmaceutical compositions which can be administered as a foam by means of a propellant free delivery device. The pharmaceutical composition comprises a surfactant, a solvent, an active ingredient and optionally a mucoadhesive polymer. Alkylamidobetaine, quarternary ammonium salts, poloxamers (polyoxyethylene-polyoxypropylene) copolymers and phospholipids are disclosed as surfactants. Unfortunately, the use of these surfactants limits the types of active ingredients that are compatible with these surfactants and that can be included in the pharmaceutical composition.
In view of the many different specific applications of foamable medicinal or hygiene systems, it is evident that the few known systems cannot satisfy all needs. Accordingly, one object of the present invention is to provide another system for delivering a mucosal or cutaneous medicinal or hygiene composition in the form of a foam. A preferred object of the present invention is to provide a system for delivering a mucosal or cutaneous medicinal or hygiene composition in the form of a foam which can be administered with a spoon without spilling even if the spoon is not kept in horizontal position. It is another preferred object of the present invention to provide such system which is capable of delivering a self-sustainable foam of which the duration can be controlled and if desirable varied without the need of mixing a plurality of foaming agents.